Detection of a typhus group Rickettsia in Amblyomma ticks in the state of Nuevo Leon, Mexico.

: The state of Nuevo Leon, Mexico has had outbreaks of typhus group rickettsiosis, most recently recognized in 1997. Evaluation of the sera of 345 patients with a dengue-like illness revealed that 25.5% had antibodies reactive with typhus group rickettsiae and 16% had antibodies to Rickettsia parkeri. Rickettsiae were detected by PCR and shell-vial isolations in the field-collected Amblyomma ticks. Molecular characterization by DNA sequence analysis of the gltA, ompB, and 17-kDa gene identified the organisms to be R. prowazekii.